Manufacture of textile and other materials having a basis of cellulose triacetate



United States PatentO .MANUEA'CTURE OF TEXTILE AND OTHER LMATERIALS .HAVING .A BASIS OF CELLU- LOSE .TRIACETATE bSelwyn George Hawtin andJohn Downing, Spondon, :nearDerby, England, assignorsqto British Celanese Limited, a corporation of Great Britain NoDrawing. Application January 9,1957 Serial No. 633,194

;Claims priority, application Great Britain January 11,1956

-9 Claims. (Cl. 106193) This invention relates to the manufacture of artificial textile and other materials'having a basis of cellulose triacetate and containing an effect material, for example a-pigment or dyestuif.

It is known that artificial textile and other materials can 'be made both from acetone-soluble cellulose acetates having an acetyl value usually between 51.5 and 55% (reckoned as acetic acid, as throughout this specification), and also from cellulose triacetates, i.e. cellulose "acetates of acetyl value above 59% and preferably above 60%. The materials produced from the two types of cellulose acetates, while both valuable, differ considerably in their properties, and thus to a considerable degree servedifr'erent purposes. *In particular cellulose triacetate textile materials can be obtained in a form characterized by a very high safe ironing temperature and other valuable properties ,by a treatment with dry heat, wet steam or .hotwater, as described in U.S. applications. No. 400,798, filed December 28, 1953, or with an organic liquid or vapour which is a swelling agent for cellulose triacetate, .as described in U.S. application S. No. 467,223, filed November 5, 1954. This is .notpossible with materials of acetone-soluble cellulose .acetate.

.It is also known to .make acetone-soluble cellulose acetate textile materials containing effect materials by .spinning a solution ofthe cellulose acetate which contains the effect material, usually a pigment or a dyestuff. ,Especially when .the elfect material .is insoluble in the spinning solution, it is necessary to take special precautions to ensure its uniform distribution in'the .form of particles small enough .to pass ffreely .through the'spinning orifices. he preferred method of doing-this involves the production of so-called lacquer chips, whichare .solid particles of the cellulose Iacetate containing the finely divided effect ,material. When these lacquer chips are dissolved the .effect material retains its finely divided ,form, and .does

not agglomerate to any significant'extent. The lacquer chips may be mixed with cellulose acetate free from efiect materials and the mixture dissolved to form a spinning solution, or they may be added to and dissolved in anal- .ready existing spinning solution, or they may be used to 'form a concentrate, i.e. a cellulose acetate solution con- .taining a relatively high proportion of the effect material which is mixed withthe main spinning solution shortly before'the actual extrusion, soavoiding contaminating the whole spinning solution supply system .with the effect material.

We have now found that-cellulose triacetate textile and :otherarticles (in the sense of articles having substantially .the same characteristicproperties 'as the cellulose tri acetate articles made in the past) containing effectma- ,terialscan be made by the lacquer chip method-using as'the basis of-the lacquer chips an acetone-solublecellu- .loseacetate. This discovery is --of considerable practical value, as itmakes it possible to produce articles having ,forexample the same .colourzof both acetone-soluble cellui ate'n tecl Mar. 31, 1959 lose acetate-andtcellulose triacetate using lacquer chips from a single source.

"times a spinning solution although, as is shown below,

it can be shaped by other methods.) Solvents consisting mainly or entirely of methylene chloride or ethylene chlorideare particularly suitable for use in the process oftthe invention, but other solvents for both acetone-soluble cellulose acetate and cellulose triacetate can be employed, for example acetic acid. Preferably the solution contains not more than 15%, and especially not more than -'8%, say 18%, of the acetone-soluble cellulose acetate, based on the weight of the cellulose triacetate.

In the preferred method of carrying out the process of the invention, the acetone-soluble cellulose acetate containing the finely divided efiect material is dissolved in'a relatively small amount of a solvent to form a'concentrate, and the concentrate is then added to a solution of cellulose triacetate, preferably in a solvent of substantially identical composition, the resulting solution beingshaped and coagulated to form the desired article.

When, aswill usually be the case, it is desired to-produce spinning operation. On the other hand attractive effects,

involving for example differential colouring, can be obtained when the solution as spun is not uniform; for instance the concentrate may be added intermittently or at varying rates to a stream of the main spinning solution, and the resulting solution spun without making it'homogeneous throughout.

Other methods of carrying out the invention mayalso be employed. Thus small particles or chips ofthe acetone-soluble cellulose acetate containing the effect material may be added directly to, and dissolved in, "a

cellulose triacetate spinning solution, or the-spinning 'solu- -tion may be made by dissolving a mixture of the cellulose triacetate with a suitably smaller proportion of'the acetone-soluble cellulose acetate containing the effect material.

The most important application of the invention is'in the production of artificial filamentary materials by known spinning methods, and the invention will befurther described with reference to the production of'such materials. It will however be realised that the solutions containing the cellulose triacetate and the-efiect material can'beused also in the manufacture of other articles, e.g. of films, foils and the like by extrusion or casting processes.

"Thelacquer chips are preferably made by the method described for example in US. Patent No. 2,70l,21l,-in which the acetone-soluble cellulose acetate, the effect material, and a softening agent are thoroughly worked on malaxating rolls under conditions such that eventually substantially all the softening agent evaporates.

The/softening agent may be-a volatile solvent suchas acetone, or a higher boiling agent, e.g. a compound boiling between and C. such as glycol monomethyl or monoethyl ether, diacetone alcohol ('Z-hydroxy-2-methyl-pentanone-4), glycol monomethyl ether acetate, or ethyl lactate. Especially when acetone is used it is important that any residual softening agent .should be present in very small amounts, e.g. below' 0.5% 'of the weight of the cellulose acetate, so as;t0;avoid subsequent difliculties in the filtration; of the spinningiscr weight.

lution containing the effect material. If desired the lacquer chips may be extracted with water before use, as described in U.S. Patent No. 2,701,211.

'It is usually desirable that the chips should contain a high proportion of the effect material; for example they may contain more than and especially -100%, of the effect material, based on the Weight of the cellulose acetate. The proportion of the chips incorporated in the spinning solution will usually be such as to give a concentration of the effect material between about 0.5 and 2% (on the cellulose triacetate) but proportions outside this range can be used when it is so desired.

The effect materials most commonly used are pigments and dyes, but the term as used in this specification includes also other substances 'such for example as fireretardants, filling materials, softening agents, sizes, resinous materials, catalytic reagents and lubricants.

For example, the eflFect material may be a white pigment employed to give subdued lustre and a high degree of opacity. Examples of suitable white inorganic pigments are tin oxide, tin phosphate, antimony oxide, titanium dioxide, barium sulphate, lead sulphate, calcium sulphate, zinc oxide, zinc carbonate, silicon dioxide, barium borate, calcium borate, and silicates such as china clay and other clays, talc and mica. Examples of suitable organic pigments are diacetyl-benzidine, diacetyltoluidine, dibenzoyl-benzidine, naphthyl-urea and suitable synthetic and natural resins.

To obtain coloured yarns, suitable colour pigments may be employed. Examples of yellow pigments are ochre, sienne, chrome yellow, tin bronze. Examples of red pigments are Venetian red, red lead, vermillion. Examples of blue pigments are ultramarine, Prussian blue, Milori blue. Examples of green pigments are Guignets green, verdigris, chrome green. Examples of brown pigments are raw umber, burnt umber, Vandyke brown. Lakes containing, for example, aluminium or tungstic acid may be used as pigments when it is desired to obtain yarns of extreme general fastness to commercial processing and domestic use. To obtain metallic effects finely divided or colloidal metals may be employed, and nacreous effects may be obtained with pearl essences, such as fish scales, nacreous mercurous chloride and nacreous lead iodide. For shading, that is to get darker colours, lamp-black, graphite or other dark pigments may be added. To obtain any other colours, suitable pigments may be mixed as is well understood in the paint art.

Examples of organic colouring materials that may be used include vat colouring materials such as dimethoxybenzanthrone and anthraquinone carbazoles, azo pigments, the phthalocyanine pigments, and water-soluble dyes such as the acid wool dyes. If desired dyes capable of dyeing cellulose acetate from aqueous dispersions, e.g. of the azo, amino-anthraquinone and nitroaromatic amine series, may be used, but such dyes can as a rule be easily dispersed in the spinning solution without resorting to the lacquer chip technique.

Examples of fire-retardants are beta-chloronaphthalene, trichloroethyl phosphate, triphenyl phosphate and tricresyl phosphate. Examples of softening agents are the oleates and stearates of glycol, glycerol and triethanolamine.

As stated above, the spinning solvent will usually consist primarily of methylene chloride or ethylene chloride. Methylene chloride is preferred, partly on general grounds and partly because it is the better solvent for acetone-soluble cellulose acetate. It is advantageous to employ the methylene or ethylene chloride in admixture with a minor proportion, e.g. 4-16% by weight (on the total solvent), of a lower aliphatic monohydric alcohol, especially methanol or ethanol. A preferred solvent is a mixture of methylene chloride and methanol containing about 6-14% of methanol by The concentration of the cellulose triacetate in the solution may be such as is usually employed in spinning, e.g. round about 20-25%, depending to some extent on the viscosity of the cellulose triacetate, and on the proportion of acetone-soluble cellulose acetate, and of any further solvent, incorporated in the solution.

When it is desired to obtain a uniform product the spinning solution containing the effect material should be agitated or mixed, e.g. in a mixing machine and/or by pumping it repeatedly round a circuit as described in U.S. Patent No. 2,156,201 and U.S. application S. No. 321,686, filed November 20, 1952, until the effect material is absolutely uniformly dispersed through the whole of the solution.

Filamentary materials may be made from the spinning solutions containing the effect materials by dry spinning, especially when the solvent consists mainly or entirely of methylene chloride, and by wet spinning, e.g. into a coagulating bath consisting primarily of a lower aliphatic alcohol such as isopropanol, ethanol or methanol when the spinning solvent consists mainly or entirely of methylene chloride. Methods of dry and wet spinning solutions of cellulose triacetate in methylene chloride or mixture of methylene chloride with methanol are known and need not be further described here, as also is the wet spinning of acetic acid solutions of cellulose triacetate into aqueous acetic acid.

As already stated the products obtained have the characteristic properties of cellulose triacetate textile and other articles. For example textile articles obtained in accordance with the invention may be given a heat treatment or a treatment with steam or hot water as described in U.S. application S. No. 400,798, or with solvents or swelling agents as described in U.S. application S. No. 467,223, whereby their safe ironing temperature is increased, e.g. to about 240 C.

The invention is illustrated by the following examples. All parts and proportions are by weight unless otherwise stated.

Example I Lacquer chips were made by working on malaxating rollers a composition comprising parts of an acetonesoluble cellulose acetate of acetyl value about 53.5% and 20 parts of the pigment Irgalite Green DBN, together with enough diacetone alcohol and water to keep the composition plastic in the early stages. One of the rollers was heated, and working was continued until substantially the whole of the diacetone alcohol and water had been driven off, and a cellulose acetate sheet in which the pigment was uniformly distributed had been formed. This sheet was then broken up to form the chips.

The chips were then added to a 20% (weight/volume) solution of cellulose triacetate in a mixture of 93% methylene chloride and 7% methanol containing 0.5% (on the weight of the triacetate) of titanium dioxide. The proportion of chips added was such that the ratio of acetone-soluble cellulose acetate to cellulose triacetate in the resulting solution was 1:19. The chips and the cellulose triacetate solution were vigorously mixed in a Werner-Pfleiderer mixer for eight hours.

The pigmented solution so obtained was extruded through a spinning jet into a current of hot air, and the resulting filaments wound up as a yarn at a rate of 300 metres per minute. The yarn was uniformly coloured, and had a tenacity of 1.03 gm. per denier and an extensibility of 16.0%.

Example II Lacquer chips obtained as in Example I were dissolved in a mixture of 93% methylene chloride and 7% methanol to give a solution of cellulose acetate concentration about 20% (weight/volume). This solution or concentrate was continuously fed into a stream of a 20% (weight/volume) solution of cellulose triacetate in't'he same solvent mixture, at a ratio of 1 volume of concentrate to 20 of the cellulose triacetate solution. The resulting pigmented solution was rendered thoroughly homogeneous and then dry spun as described in Example 1.

Having described our invention, what we desire to secure by Letters Patent is:

1. Process for the manufacture of textile and other articles having a basis of cellulose triacetate and containing an cifect material, which comprises forming a spinning solution by dissolving in a solvent common to both (a) cellulose triacetate and (b) acetone-soluble cellulose acetate in amount at most 15% of the weight of the cellulose triacetate and containing an effect material finely dispersed in it, and shaping and coagulating the said spinning solution.

2. Process for the manufacture of textile and other articles having a basis of cellulose triacetate and containing an effect material, which comprises adding a particulate acetone-soluble cellulose acetate in which an effect material has been finely dispersed to a solution of a cellulose triacetate, the amount of the said particulate acetonesoluble cellulose acetate being l-8% of the weight of the cellulose triacetate, and after the acetone-soluble cellulose acetate has all dissolved shaping and coagulating the resulting spinning solution.

3. Process for the manufacture of textile and other articles having a basis of cellulose triacetate and containing an eflect material, which comprises adding a concentrate to a solution of a cellulose triacetate, said concentrate being obtained by dissolving an acetone-soluble cellulose acetate in which an effect material has been finely dispersed, the relative amounts and the compositions of the concentrate and the cellulose triacetate solution respectively being such that the amount of acetone-soluble cellulose acetate in the resulting spinning solution is l-8% of the weight of the cellulose triacetate, and shaping and coagulating the said spinning solution.

4-. Process for the manufacture of textile and other articles having a basis of cellulose triacetate and con taining an effect material, which comprises adding a particulate acetone-soluble cellulose acetate in which an effect material has been finely dispersed to a solution of a cellulose triacetate in a mixture of methylene chloride and methanol containing 6-14% by weight of methanol,

the amount of the said particulate acetone-soluble cellulose acetate being 1-8% of the weight of the cellulose triacetate, and after the acetone-soluble cellulose acetate has all dissolved shaping and coagulating the resulting spinning solution.

5. Process for the manufacture of textile and other articles having a basis of cellulose triacetate and containing an effect material, which comprises adding a concentrate, obtained by dissolving an acetone-soluble cellulose acetate in which an effect material has been finely dispersed, to a solution of a cellulose triacetate, the relative amounts and the compositions of the concentrate and the cellulose triacetate solution respectively being such that the amount of acetone-soluble cellulose acetate in the resulting spinning solution is l-8% of the weight of the cellulose triacetate and the solvent component both of the concentrate and of the cellulose triacetate solution being a mixture of methylene chloride and methanol containing 6-14% by weight of methanol, and shaping and coagulating the said spinning solution.

6. Process according to claim 2, in which the particulate acetone-soluble cellulose acetate is 20-100% of the weight of the elfect material dispersed in it.

7. Process according to claim 3, in which the amount of eflt'ect material in the concentrate is 20-100% of the weight of the acetone-soluble cellulose acetate.

8. Process according to claim 2, in which the spinning solution is shaped and coagulated by dry spinning.

9. Process according to claim 3, in which the spinning solution is shaped and coagulated by dry spinning.

References Cited in the file of this patent UNITED STATES PATENTS 2,048,248 Dreyfus et al. July 21, 1936 2,085,512 Schneider June 29, 1937 2,591,077 Lamborn Apr. 1, 1952 2,701,211 Taylor et al. Feb. 1, 1955 2,739,069 Fordyce et al Mar. 20, 1956 FOREIGN PATENTS 243,031 Great Britain Feb. 17, 1927 

1. PROCESS FOR THE MANUFACTURE OF TEXTILE AND OTHER ARTICLES HAVING A BASIS OF CELLULOSE TRIACETATE AND CONTAINING AN EFFECT MATERIAL, WHICH COMPRISES FORMING A SPINNING SOLUTION BY DISSOLVING IN A SOLVENT COMMON TO BOTH (A) CELLULOSE TRIACETATE AND (B) ACETONE-SOLUBLE CELLULOSE ACETATE IN AMOUNT AT MOST 15% OF THE WEIGHT OF THE CELLULOSE TRIACETATE AND CONTAINING AN EFFECT MATERIAL FINELY DISPERSED IN IT, AND SHAPING AND COAGULATING THE SAID SPINNING SOLUTION. 